Basic and Clinical Neuroscience Journalمجله علوم اعصاب پایه و بالینیBCNMedical Scienceshttp://bcn.iums.ac.ir137journal1372008-126X2228-744210.32598/bcnenjalali139211gregorian20134142online1fulltextenFunctional Interaction between the Shell Sub-Region of the Nucleus Accumbens and the Ventral Tegmental Area in Response to Morphine: an Electrophysiological StudyCellular and molecular NeuroscienceCellular and molecular NeuroscienceOriginalOriginal<p align="left" ><p><font color="#221e1f" size="1"><font color="#221e1f" size="1">This study has examined the functional importance of nucleus accumbens (NAc)-ventral tegmental area (VTA) interactions. As it is known, this interaction is important in associative reward processes. Under urethane anesthesia, extracellular single unit recordings of the shell sub-region of the nucleus accumbens (NAcSh) neurons were employed to determine the functional contributions of the VTA to neuronal activity across NAcSh in rats. The baseline </font></font><font color="#221e1f" face="Times New Roman,Times New Roman" size="1"><font color="#221e1f" face="Times New Roman,Times New Roman" size="1"><font color="#221e1f" face="Times New Roman,Times New Roman" size="1">firing rate of NAcSh neurons varied between 0.42 and 11.44 spikes/sec and the average frequency of spontaneous activity over 45-minute period was 3.21±0.6 spikes/sec. The majority of NAcSh neurons responded excitatory in the first and second 15-min time blocks </font></font></font><font color="#221e1f" size="1"><font color="#221e1f" size="1">subsequent to the inactivation of VTA. In the next set of experiments, eight experimental rats </font></font><font color="#221e1f" face="Times New Roman,Times New Roman" size="1"><font color="#221e1f" face="Times New Roman,Times New Roman" size="1"><font color="#221e1f" face="Times New Roman,Times New Roman" size="1">received morphine (5 mg/kg sc). Three patterns of neuronal activity were found. Among the </font></font></font><font color="#221e1f" size="1"><font color="#221e1f" size="1">recorded neurons only three had an increase followed by morphine administration. Whereas the other three neurons were attenuated following morphine administration and there were </font></font><font color="#221e1f" face="Times New Roman,Times New Roman" size="1"><font color="#221e1f" face="Times New Roman,Times New Roman" size="1"><font color="#221e1f" face="Times New Roman,Times New Roman" size="1">no changes in the firing rates of the two neurons left. Finally, unilateral reversible inactivation of VTA attenuated the firing activity of the majority of ipsilateral NAcSh neuron in response </font></font></font><font color="#221e1f" size="1"><font color="#221e1f" size="1">to morphine, except for a single cell. These results suggest that transient inactivation of VTA reduces the ability of neurons in the NAcsh to respond to systemic morphine, and that NAcSh </font></font><font color="#221e1f" face="Times New Roman,Times New Roman" size="1"><font color="#221e1f" face="Times New Roman,Times New Roman" size="1"><font color="#221e1f" face="Times New Roman,Times New Roman" size="1">neuron activity depends on basal firing rate of VTA inputs. </font></font></font></p>Nucleus Accumbens,Ventral Tegmental Area,Reversible Inactivation,Single Unit Recording,Morphine,Rat.159168http://bcn.iums.ac.ir/browse.php?a_code=A-10-1-156&slc_lang=en&sid=1MahsaMoaddab13700319475328460038831370031947532846003883NoMojtabaKermani13700319475328460038841370031947532846003884NoPegahAzizi13700319475328460038851370031947532846003885NoAbbasHaghparast13700319475328460038861370031947532846003886Yes